Ionomers modified with rosin and articles thereof

ABSTRACT

Disclosed are thermoplastic compositions comprising partially or fully neutralized carboxylic acid-based ionomers modified with rosin or rosin derivatives and, optionally, organic acids and salts thereof. Methods of preparing the thermoplastic compositions are also provided. The thermoplastic compositions exhibit higher hardness and stiffness than typical ionomer compositions. Also disclosed are golf balls, sporting equipment, and other non-sport articles comprising said thermoplastic compositions and methods for their preparation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §120 to U.S.Provisional Appln. No. 60/475,723, filed on Jun. 2, 2003, and to U.S.Provisional Appln. No. 60/542,762, filed on Feb. 6, 2004, both of whichare incorporated herein in their entirety. Related U.S. Appln. No.10/859,421, concurrently filed, entitled “IONOMERS MODIFIED WITH ROSINAND ARTICLES THEREOF” is also incorporated herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to thermoplastic compositions, andspecifically to thermoplastic compositions comprising partially or fullyneutralized carboxylic acid-based ionomers modified with rosin or rosinderivatives and, optionally, organic acids and salts thereof. Thecompositions of the invention, which exhibit higher hardness andstiffness than typical ionomer compositions, may also containthermoplastic non-ionomeric polymers, fillers and/or fibers, and otheradditives.

BACKGROUND OF THE INVENTION

Several patents and publications are cited in this description in orderto more fully describe the state of the art to which this inventionpertains. The entire disclosure of each of these patents andpublications is incorporated by reference herein.

Ionomeric resins (ionomers) are copolymers of an olefin such as ethyleneand an unsaturated carboxylic acid, such as acrylic acid, methacrylicacid, or maleic acid, and optionally softening monomers, in which someportion of the acidic groups in the copolymer is neutralized with metalions such as sodium or zinc. Ionomers are thermoplastic resinsexhibiting enhanced properties, e.g. improved resilience, stiffness orsoftness, toughness, durability, etc. for golf ball cover constructionover balata (see below). As a result of their resilience, toughness,durability and cut resistance, various ionomeric resins sold by E. I. duPont de Nemours & Company of Wilmington, Del. (DuPont) under thetrademark “Surlyn®” and by the ExxonMobil Chemical Corporation ofHouston, Tex. under the tradenames “Escor™” and “lotek™” have becomematerials of choice for the construction of golf ball covers instead ofthe traditional balata (natural or synthetic rubber) covers. The softerbalata covers, although exhibiting enhanced playability, lack thedurability and cut resistance desirable for repetitive play. In additionto their improved durability, harder covers or mantles tend to minimizeball spin and maximize the straightness of the ball's travel off theclubface. Some golfers prefer golf balls that maximize distance andprovide low spin characteristics. Thus, it is desirable to continuedeveloping materials for golf balls with increased hardness andstiffness.

Current commercial ionomers derived from dipolymers have properties thatvary according to the type and amount of metal cations, molecular weightand composition of the base resin (i.e. relative content of ethylene andmethacrylic and/or acrylic acid groups). Ionomers can also be modifiedby the addition of comonomers to modify their physical properties. Forexample, terpolymers made from an olefin such as ethylene, anunsaturated carboxylic acid and other comonomers such as alkyl(meth)acrylates provide “softer” resins, which can be neutralized toform softer ionomers.

Approaches to providing harder ionomers include the use of relativelyhigh percentages of the carboxylic acid moieties in the copolymer.Disadvantageously, ethylene acid copolymers with high levels of acid aredifficult to prepare in continuous polymerizers because ofmonomer-polymer phase separation. This difficulty can be avoided by useof “co-solvent technology” as described in U.S. Pat. No. 5,028,674 or byemploying somewhat higher pressures than those at which copolymers withlower acid can be prepared. Despite these expedients, there is aninherent limit to the amount of carboxylic acid that can be incorporatedas a monomer in ethylene acid copolymers. In addition, such methodsresult in higher costs and more complex processes.

The properties of thermoplastic resins, such as ethylene acid copolymersand ionomers thereof, can also be modified by blending other componentsinto a polymer melt. For example, U.S. Pat. No. 6,608,127 describes golfballs having covers comprising an ionomeric resin modified by theaddition of terpene resin tackifiers and/or rosin ester tackifiers.Similarly, U.S. Pat. No. 6,371,869 describes golf balls having coverscomprising an ionomeric resin modified by the addition of thermoplasticelastomers and terpene resin tackifiers and/or rosin ester tackifiers.The compositions used for golf ball covers in these patents arecharacterized as having Shore D hardness of from 40 to 65.

Thus, it is desirable to develop a material for golf ball covers,mantles, intermediate layers, etc., having a combination of hardness,stiffness and good scuff resistance with improved heat stability andmelt processibility. It is particularly desirable to developcompositions of ethylene acid copolymers with low to medium acid contentthat exhibit hardness comparable to or exceeding that exhibited by highacid copolymers.

Accordingly, one object of this invention is to provide an ionomercomposition that is harder and stiffer than typical ionomericcompositions.

A further object of this invention is to provide a golf ball with a hardcover and/or intermediate layers having good resilience and durability.

A further object of this invention is to provide a golf ball having afavorable combination of low spin, durability and distance-carryingflight characteristics.

A further object of the invention is to provide a golf ball that is easyto prepare having a hard and stiff cover and/or intermediate layers. Afurther object of the invention is to provide a replacement for metaland wood components in sporting equipment, particularly golf clubs.

SUMMARY OF THE INVENTION

These and other objects of the invention can be realized by ionomercompositions that are harder than typical ionomeric resins and thatincorporate rosin and/or rosin derivatives as modifiers, and also bypreparing golf balls comprising the harder ionomer compositions of thisinvention.

Accordingly, in a first aspect, the invention provides a thermoplasticcomposition comprising an ionomer and a rosin, a rosin derivative, orboth a rosin and a rosin derivative, provided that when the rosincomponent consists of a rosin ester, the thermoplastic composition alsoincludes an organic acid, a salt of an organic acids, or both an organicacid and a salt of an organic acid.

Of note is a thermoplastic composition of the invention comprising:

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer;

(ii) from about 3 weight % to about 50 weight % of rosin, rosinderivative, or a combination of rosin and rosin derivative; andoptionally

(iii) from about 5 weight % to about 50 weight % of one or more organicacids or salts thereof; such that the combined weight % of component(ii) and component (iii) when present is from about 3 weight % to about60 weight % of the total composition; wherein the combined carboxylicacid functionalities in all ingredients in the blend are at leastpartially neutralized by one or more alkali metal, transition metal, oralkaline earth metal cations; provided that when component (ii) consistsof rosin ester, component (iii) must be present.

Of note is the composition comprising:

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer; and

(ii) from about 3 weight % to about 50 weight % of rosin; wherein thecombined carboxylic acid functionalities in all ingredients in the blendare at least partially neutralized by one or more alkali metal,transition metal, or alkaline earth metal cations.

This invention also provides the compositions above further comprisingat least one additional component selected from non-ionomericthermoplastic or thermoset polymers.

In another aspect, this invention provides a one-piece golf ballcomprising a thermoplastic composition of this invention. This inventionalso provides a one-piece golf ball consisting essentially of athermoplastic composition of this invention.

This invention also provides methods of making one-piece golf balls asdescribed above, comprising molding a composition of this invention intothe shape of a golf ball.

This invention also provides a multi-piece golf ball wherein any of thefollowing components that form the golf ball, including the cover, themantle, any intermediate layer, the core or the center, comprises athermoplastic composition of this invention.

This invention also provides a multi-piece golf ball, wherein at leastone of the components that form the golf ball comprises a thermoplasticcomposition of this invention and at least one other component comprisesa non-ionomeric thermoplastic polymer.

This invention also provides a multi-piece golf ball wherein one of thecomponents that form the golf ball consists essentially of athermoplastic composition of this invention.

This invention also provides methods of making golf balls with covers,mantles, intermediate layers, cores and/or centers as described above,comprising obtaining a golf ball core or center and forming a cover,mantle, and/or intermediate layer over the core and/or the center formedof the thermoplastic compositions of this invention.

This invention also provides methods of making golf balls as describedabove, comprising molding a composition of this invention into the shapeof golf ball mantles, intermediate layers, cores and/or centers andforming covers over them.

Also provided is a material that may replace metal and wood componentsin sporting equipment, particularly golf clubs, including an ionomer anda rosin, a rosin derivative, or both a rosin and a rosin derivative.

Of note is a composition comprising:

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer;

(ii) from about 3 weight % to about 50 weight % of rosin, rosinderivative, or a combination of rosin and rosin derivative; andoptionally

(iii) from about 5 weight % to about 50 weight % of one or more organicacids or salts thereof; such that the combined weight % of component(ii) and component (iii) when present is from about 3 weight % to about60 weight % of the total composition; wherein the combined carboxylicacid functionalities in all ingredients in the blend are at leastpartially neutralized by one or more alkali metal, transition metal, oralkaline earth metal cations.

In another aspect, a molded article selected from the group consistingof sports shoe cleats, golf club face plates or inserts, molded golfclub heads, club head coatings or casings, fillers for the inner cavityof a golf club head, and footwear structural components comprises theabove thermoplastic composition of the invention.

In another aspect, this invention also provides a caulking material,sealant, modifier for cement and asphalt, or coating comprising theabove thermoplastic composition of the invention.

DETAILED DESCRIPTION OF THE INVENTION

“Copolymer” means polymers containing two or more different monomers.The terms “dipolymer” and “terpolymer” mean polymers containing only twoand three different monomers respectively. The phrase “copolymer ofvarious monomers” means a copolymer whose units are derived from thevarious monomers.

Thermoplastic compositions are polymeric materials that flow when heatedunder pressure. Melt index (MI) is the rate of flow of a polymer througha specified capillary under controlled conditions of temperature andpressure. Melt indices reported herein are determined according to ASTM1238 at 190° C. using a 2160 g weight, with values of MI reported ingrams/10 minutes.

Ionomeric resins (“ionomers”) are copolymers of an olefin, such asethylene, and an unsaturated carboxylic acid, such as acrylic acid,methacrylic acid, or maleic acid, in which at least a portion of theacid groups is neutralized with at least one alkali metal, transitionmetal, or alkaline earth metal cation, such as lithium, sodium,potassium, magnesium, calcium, or zinc, or a combination of suchcations, is used to neutralize some portion of the acidic groups in thecopolymer.

The term “(meth)acrylic”, as used herein, alone or in combined form,such as “(meth)acrylate”, refers to acrylic and/or methacrylic, forexample, acrylic acid and/or methacrylic acid, or alkyl acrylate and/oralkyl methacrylate. In this connection, “ethylene/(meth)acrylic acid(abbreviated E/(M)AA)” means a copolymer of ethylene (abbreviatedE)/acrylic acid (abbreviated AA) and/or methacrylic acid (abbreviatedMAA), which can then be at least partially neutralized by one or morealkali metal, transition metal, or alkaline earth metal cations to forman ionomer.

The term “rosin” as used herein, alone or in combined form, e.g.,rosinic or rosinate, includes natural or modified rosins, natural ormodified rosin acids, purified natural or modified rosin acids, salts ofnatural or modified rosin acids, including partially to completelyneutralized mixtures of acids and salts, and combinations of one or moreof the above rosins. Modifications of rosins, rosin acids, and rosinsalts include hydrogenation, epoxidation, dimerization, and the like.Derivatizations of modified or natural rosins, rosin acids, and rosinsalts include esterification, amidization, and the like.

The term “finite amount”, as used herein, refers to an amount that isnot equal to zero.

As used herein, the term “about” means that amounts, sizes,formulations, parameters, and other quantities and characteristics arenot and need not be exact, but may be approximate and/or larger orsmaller, as desired, reflecting tolerances, conversion factors, roundingoff, measurement error and the like, and other factors known to those ofskill in the art. In general, an amount, size, formulation, parameter orother quantity or characteristic is “about” or “approximate” whether ornot expressly stated to be such.

Some thermoplastic compositions of the invention preferred for use ingolf balls include an ionomer and a rosin, a rosin derivative, or both arosin and a rosin derivative, provided that when the rosin componentconsists of rosin ester, the thermoplastic composition also includes anorganic acid, a salt of an organic acid, or both an organic acid and asalt of an organic acid.

Suitable precursors for the ionomers useful in the present invention areacid copolymers, preferably “direct” acid copolymers. They arepreferably copolymers of an alpha olefin, more preferably ethylene, witha C₃ to C₈, α,β ethylenically unsaturated carboxylic acid, morepreferably (meth)acrylic acid.

The acid copolymers may optionally contain a third “softening” monomerthat disrupts the crystallinity of the polymer. These acid copolymers,when the alpha olefin is ethylene, can be described as E/X/Y copolymerswherein E is ethylene, X is the α,β ethylenically unsaturated carboxylicacid (as described above), particularly acrylic and methacrylic acid,and Y is the softening co-monomer. Preferred softening co-monomers areC₁ to C₈ alkyl acrylate or methacrylate esters. Other softeningcomonomers include maleic anhydride and maleic acid mono-esters. X and Ycan be present in a wide range of percentages, X typically up to about35 weight percent (wt. %) of the polymer and Y typically up to about 50weight percent of the copolymer.

The copolymer(s) of alpha olefin, C₃ to C₈ α,β ethylenically unsaturatedcarboxylic acid and optional softening monomer from which the meltprocessible ionomers described above are prepared can be made by methodsknown in the art. Suitable copolymers include, without limitation,ethylene acid copolymers, such as ethylene/(meth)acrylic acid,ethylene/(meth)acrylic acid/maleic anhydride, ethylene/(meth)acrylicacid/maleic acid mono-ester, ethylene/maleic acid, ethylene/maleic acidmono-ester, ethylene/(meth)acrylic acid/n-butyl (meth)acrylate,ethylene/(meth)acrylic acid/iso-butyl (meth)acrylate,ethylene/(meth)acrylic acid/methyl (meth)acrylate,ethylene/(meth)acrylic acid/ethyl (meth)acrylate terpolymers, and thelike.

Suitable ionomers for use in the invention include melt-processible, atleast partially neutralized copolymers of ethylene and C₃ to C₈ α,βethylenically unsaturated carboxylic acids. Preferred ionomers for usein the present invention include E/(M)AA dipolymers having from about 2to about 30 weight % (M)AA, at least partially neutralized by one ormore alkali metal, transition metal, or alkaline earth metal cations.Methods of neutralizing acid copolymers to form ionomers are well knownin the art.

Rosin is the residue left after distilling off the volatile oil from theoleoresin obtained from Pinus palustris and other species of Pinus,Pinaceae. It is available as wood rosin (from Southern pine stumps), gumrosin (the exudates from incisions in the living tree, P. palustris andP. caribaea), and tall oil rosin. Rosin typically contains about 90%rosin acids and about 10% neutral matter. Of the rosin acids about 90%are isomeric with abietic acid (C₂₀H₃₀O₂); the other 10% is a mixture ofdihydroabietic acid (C₂₀H₃₂O₂) and dehydroabietic acid (C₂₀H₂₈O₂). (SeeThe Merck Index, Tenth Ed. Rahway, N.J., USA, 1983, page 1191, entry8134). Rosin acids can also be obtained from tall oil, also known asliquid rosin, which is a byproduct of the wood pulp industry and isusually recovered from pine wood “black liquor” of the sulfate or kraftpaper process. Tall oil contains rosin acids (34-40%), fatty acids suchas oleic and linoleic acids (50-60%) and neutral matter (5-10%). (SeeThe Merck Index, Tenth Ed., page 1299, entry 8917).

The acids present in natural rosin may be purified by, for example,saponification, extraction of the neutral matter and reacidification.The free acid moieties in rosins can be modified by, for example,forming carboxylate salts by saponification to provide partially tocompletely neutralized salts with metal ions, e.g. resinate. Rosin acidscan also be modified by chemical processes such as hydrogenation,dimerization, epoxidation, etc., that alter that chemical structure ofthe molecules while leaving the acidic functionalities unaffected.

Rosin is available commercially in several grades, for example, underthe tradename “Resinall™” from Resinall Corporation, of Stamford, Conn.(Resinall), and like products supplied by Hercules of Wilmington, Del.,Eastman Chemical Company of Kingsport, Tenn. (Eastman), Arakawa Chemical(USA), Inc., of Chicago, Ill., and others.

Derivatives of rosin can also be prepared by reacting at least a portionof its carboxylic acid moieties, or of the carboxylate anions or acidchloride groups or the like, with moieties that form covalent bonds withthe carboxylic carbonyl group, thereby rendering the rosin non-acidicand/or incapable of forming carboxylate salts. Examples of rosinderivatives include rosin esters, which may be prepared byesterification of the carboxylic acid moieties with alcohol moieties;and rosin amides, which may be prepared by reaction of the carboxylicacid moieties (or derivatives thereof such as the aforementioned estersand acid chloride) with amine moieties. Rosin esters are preferred rosinderivatives for use in the present invention.

Preferably, one rosin or one rosin derivative is included in thethermoplastic compositions of the invention. Combinations of more thanone rosin, combinations of more than one rosin derivative, andcombinations of at least one rosin with at least one rosin derivativeare also contemplated, however.

The compositions of this invention are comprised of mixtures of acidcopolymer(s) and at least one rosin or rosin derivative that are atleast partially neutralized by at least one of the alkali metal,alkaline earth metal or transition metal cations. Preferably at least30%, alternatively at least 45%, alternatively at least 50%,alternatively at least 60% of the available acid moieties in thecomposition are neutralized. Cations are preferably selected from thegroup consisting of lithium*, sodium*, potassium, magnesium*, calcium*,barium, lead, tin, or zinc* (* indicates a more preferred cation), or acombination of such cations.

Moreover, additional neutralizing agent may be added to ionomer-rosinblends to achieve the desired state of neutralization. It will beapparent to those of skill in the art, however, that the effect ofadding an additional neutralizing agent is to produce an ionomer blendthat includes a rosin salt, or both a rosin and a rosin salt.

The organic acids that may be optionally employed in the presentinvention are those that are non-volatile and non-migratory. Organicacids that may be employed in the present invention include aliphatic,mono-functional (saturated, unsaturated, or multi-unsaturated) organicacids, particularly those having from 6 to 36 carbon atoms. Also, saltsof these organic acids may be employed. Linear saturated fatty acids orfatty acid salts are preferred, particularly mono-functional organicacid(s) having from 6 to 36 carbon atoms or salts thereof.

Preferred organic acids useful in the present invention include caproicacid, caprylic acid, capric acid, lauric acid, stearic acid, behenicacid, palmitic acid and myristic acid. Stearic, behenic, palmitic andmyristic acids are more preferred.

Preferably, one organic acid or one organic acid salt is included in thethermoplastic compositions of the invention. Combinations of more thanone organic acid, combinations of one or more organic acid salts, andcombinations of at least one organic acid with at least one organic acidsalt are also contemplated, however.

Moreover, additional neutralizing agent may be added to blends includingone or more organic acids to achieve the desired state ofneutralization. It will be apparent to those of skill in the art,however, that the effect of adding an organic acid and an additionalneutralizing agent is to produce a polymer blend that includes a salt ofan organic acid, or both an organic acid and a salt of an organic acid.

The rosin or rosins and, optionally, one or more organic acids and/orsalts thereof are added in an amount sufficient to enhance the hardnessand/or stiffness properties of the composition over the non-modifiedionomer. The rosin or rosins and optional organic acids and/or salts arepreferably added in an amount of at least about 3% (weight basis) up toabout 50% (weight basis) or about 60% (weight basis) of the total amountof the thermoplastic composition or blend. More preferably, the rosin orrosins and optional organic acids and/or salts thereof are added in anamount of at least about 8 or 10 weight %. Of note are compositionswherein the rosin or rosins and optional organic acids and/or saltsthereof are added in an amount of at least about 20 weight %, and morepreferably at least about 25 weight %.

Alternatively, one or more rosin derivatives and one or more organicacids and/or salts thereof are added in an amount sufficient to enhancethe hardness and/or stiffness properties of the composition over thenon-modified ionomer. The rosin derivative or derivatives may be addedin an amount from about 3 weight % to about 50 weight %, and the one ormore organic acids or salts thereof may also be added in an amount fromabout 5 weight % to about 50 weight % such that the combined weight % ofthe rosin derivative or derivatives and the one or more organic acidsand/or salts is from about 8 or 10 weight % to about 50 or 60 weight %of the total amount of the thermoplastic composition of the invention.Of note are compositions wherein the rosin derivative or derivatives andoptional organic acids and/or salts thereof are added in an amount of atleast about 20 weight %, and more preferably at least about 25 weight %.

Also alternatively, when one or more rosins and one or more rosinderivatives are used in combination with, optionally, one or moreorganic acids and/or salts thereof, they are added in an amountsufficient to enhance the hardness properties of the composition overthe non-modified ionomer. The rosins and/or rosin derivatives andoptional organic acids and/or salts are preferably added in an amount ofat least about 3% (weight basis) up to about 50% (weight basis) or about60% (weight basis) of the total amount of the thermoplastic compositionor blend. More preferably, the rosins and rosin derivatives and optionalorganic acids and/or salts thereof are added in an amount of at leastabout 8 or 10 weight %. Of note are compositions wherein the rosins androsin derivatives and optional organic acids and/or salts thereof areadded in an amount of at least about 20 weight %, and more preferably atleast about 25 weight %.

As indicated above, the hard ionomer compositions described above mayalso be blended with additional non-ionomeric thermoplastic polymers.Suitable non-ionomeric thermoplastic resins include, without limitation,thermoplastic elastomers, such as polyurethane, poly-ether-ester,poly-amide-ether, polyether-urea, Pebax™ (a family of block copolymersbased on polyether-block-amide, commercially supplied by Atochem ofPhiladelphia, Pa.), styrene-butadiene-styrene (SBS) block copolymers,styrene-(ethylene-butylene)-styrene block copolymers, etc., polyamide(oligomeric and polymeric), polyesters, polyolefins includingpolyethylene, polypropylene, ethylene/propylene copolymers, etc.,ethylene copolymers with various comonomers, such as vinyl acetate,(meth)acrylates, (meth)acrylic acid, epoxy-functionalized monomers, CO,etc., polycarbonates, acrylics, such as methyl methacrylate homopolymersor copolymers, polystyrene, polymers functionalized with maleicanhydride, epoxidization etc., either by copolymerization or bygrafting, elastomers such as EPDM, metallocene catalyzed PE andcopolymer, ground-up powders of the thermoset elastomers, etc.

The thermoplastic composition of the invention may contain up to 200parts by weight of thermoplastic non-ionomeric polymers based on 100parts by weight of the hard ionomer blend.

An optional filler may be included in the thermoplastic composition ofthe invention to impart additional density to the ionomers or blendsthereof with other materials. Preferred densities for the filledcompositions include densities in the range starting with the density ofunfilled polymer to 1.8 gm/cc. Generally, the filler will be inorganic,having a density greater than about 4 gm/cc, preferably greater than 5gm/cc, and will be present in amounts between 0 and about 60 weight %based on the total weight of the composition. Examples of useful fillersinclude zinc oxide, barium sulfate, lead silicate and tungsten carbide,tin oxide, as well as the other well known corresponding salts andoxides thereof. It is preferred that the filler materials benon-reactive or almost non-reactive with the polymer componentsdescribed above when the ionomers are less than completely neutralized.If the ionomers are fully neutralized, reactive fillers may be used.Zinc oxide grades, such as grade XX503R, available from Zinc Corporationof America of Monaca, Pa., that do not react readily with any free acidto cause cross-linking and a concomitant drop in MI are preferred,particularly when the ionomer is not fully neutralized.

The composition of the invention may contain up to 170 parts by weightof one or more fillers based on 100 parts by weight of the hard ionomerblend.

Other additives suitable for use in the present invention includetitanium dioxide, which may be used as a whitening agent or filler;other pigments; optical brighteners; surfactants; processing aids; etc.

Fibers, including chopped fibers or pulp, and inorganic or organicmaterials, may also be included in the compositions of this invention toprovide, for example, reinforcement or abrasion resistance.

The polymer compositions of the present invention may also include suchother additives as are commonly used in thermoplastic compositions, forexample stabilizers and processing aids. Suitable levels of theseadditives and methods of incorporating additives into polymercompositions are known to those of skill in the art. See, e.g. “ModernPlastics Encyclopedia”, McGraw-Hill, New York, N.Y. 1995.

Briefly, to prepare certain thermoplastic compositions of the invention,one or more ionomers are blended with a rosin and/or a rosin derivative,and, optionally, one or more organic acids or salts thereof.

More specifically, the rosin-modified ionomers of the invention may beproduced by

(a) melt-blending (1) ethylene, an, ethylenically unsaturated C₃ to C₈carboxylic acid copolymer(s) or melt-processible ionomer(s) thereof(including copolymers with the optional addition of a softening monomer)with (2) sufficient rosin and/or rosin derivatives, and (3) optionally,sufficient non-volatile, non-migratory organic acids or salts thereof,and, concurrently or subsequently,

(b) adding a sufficient amount of a source of cations in the presence ofadded water to achieve the desired level of neutralization of all theacid moieties, including those in the acid copolymer, rosin, and, ifpresent, the non-volatile, non-migratory organic acids.

Alternatively, the thermoplastic compositions of the invention can bemade by melt blending the rosin and/or rosin derivative and, optionally,organic acid (or salt thereof) with a melt processible ionomer and then,if necessary, further neutralizing with the same or different cations toachieve desired levels of neutralization of the resulting blend.

Also alternatively, the non-neutralized ethylene acid copolymers, rosinand/or rosin derivative, and optional organic acids or salts may bemelt-blended and neutralized in situ, e.g., in an extruder. In this casethe blending and the desired level of neutralization can be achieved inone step.

For example, ethylene copolymers containing (meth)acrylic acid can bemelt blended with rosin, rosin salts, and, optionally, calcium stearate(or calcium salts of other organic acids); or, alternatively, with rosinand optionally stearic acid (or other organic acids), and neutralized insitu with a cation source such as sodium hydroxide to convert the rosinand stearic acid-modified copolymers into rosin salt andstearate-modified ionomers of various degrees of neutralization, up toand including 100%.

Compositions with mixed ions may be prepared by treating an alreadypartially neutralized ionomer or ionomer blend with one or more sourcesof different cations. For example, an ionomer or ionomer blend that hasbeen less than fully neutralized with sodium hydroxide can be modifiedto form an ionomer or ionomer blend with a mixture of sodium andmagnesium ions. The mixed-cation ionomer or ionomer blend may beprepared by melt-processing the sodium ionomer or ionomer blend with anamount of magnesium hydroxide sufficient to neutralize some of thepreviously unneutralized acid functionalities of the sodium ionomer.

As a further example, employing a Werner & Pfleiderer (W&P) twin-screwextruder, available from Werner & Pfleiderer Lebensmitteltechnik GmbH ofDinkelsbuehl, Germany, an acid copolymer may be pre-blended with anamount of magnesium hydroxide stoichiometrically sufficient toneutralize the acid copolymer, and with a rosin and/or rosinderivatives, and, optionally, with one or more organic acids or salts oforganic acids, yielding a pellet blend. The pellet blend is melt-mixedand neutralized in the W&P twin-screw extruder in the presence of addedwater.

The compositions of this invention exhibit Shore D hardness above 40,and typically greater than or equal to about 50, 55, or 60. Preferredare compositions exhibiting Shore D hardness greater than or equal to 65and more preferred are compositions exhibiting Shore D hardness greaterthan or equal to 70 or 75.

The compositions of this invention exhibit flex modulus above 50 kpsi,and typically greater than or equal to 60 kpsi. Of note are compositionsexhibiting flex modulus greater than or equal to 65 kpsi andcompositions exhibiting flex modulus greater than or equal to 70 kpsi.Preferred are compositions exhibiting modulus of greater than or equalto 75 kpsi, alternatively greater than or equal to 80 kpsi,alternatively greater than or equal to 90 kpsi, alternatively greaterthan or equal to 100 kpsi.

The thermoplastic compositions of the invention provide manyadvantageous physical properties. For example, rosin-modified ionomersof this invention may exhibit increased stiffness, Shore D hardness,flex moduli, and/or Atti compression compared to the non-modifiedionomers. Also, rosin blends of ionomers with relatively low acidmonomer content may be as hard as or harder than ionomers withrelatively high acid monomer content.

One significant synergistic effect provided by the invention is thatrelatively hard or stiff compositions of the invention provideunexpected enhancements in resilience. For example, a two-piece golfball covered with a relatively hard or stiff composition of thisinvention may surprisingly exhibit a higher coefficient of restitutionthan is exhibited by a two-piece ball consisting of an identical corecovered with a more resilient composition. Likewise, a multilayer golfball having a mantle or intermediate layer comprising a relatively hardor stiff composition of this invention may also unexpectedly exhibit ahigher coefficient of restitution than is exhibited by a multilayer ballthat is otherwise identical but for a more resilient material in thecorresponding mantle or intermediate layer.

Furthermore, rosin type has a highly significant effect on the physicalproperties of the rosin-ionomer blends. It follows that the propertiesof the thermoplastic composition of the invention may be tailoredsystematically through rosin choice. The ratio of flex modulus tohardness, for example, varies significantly depending on rosin choicealone. Likewise, the melt indices of otherwise identical blends thatdiffer only in the choice of rosin may range over more than an order ofmagnitude. Similar significant variations may be found in measurementsof the flex moduli of otherwise identical blends.

Many of these desirable physical properties, and the relative ease withwhich they may be adjusted, will be advantageously used to optimize theperformance profiles of golf balls.

Uses of the Hard Ionomer Composition in Golf Balls

The hard ionomer blends described herein are useful substitutions forone or more materials taught in the art at the levels taught in the artfor use in covers, mantles, intermediate layers, cores, and centers ofgolf balls, or one-piece golf balls. See, for examples of materials forcovers of golf balls, U.S. Pat. Nos. 4,274,637; 4,264,075; 4,323,247;4,337,947, 4,398,000; 4,526,375; 4,567,219; 4,674,751; 4,884,814;4,911,451; 4,984,804; 4,986,545; 5,000,459; 5,068,151; 5,098,105;5,120,791; 5,155,157; 5,197,740; 5,222,739; 5,253,871; 5,298,571;5,321,089; 5,328,959; 5,330,837; 5,338,038; 5,338,610; 5,359,000;5,368,304; 5,567,772; 5,757,483; 5,810,678; 5,873,796; 5,902,855;5,971,870; 5,971,871; 5,971,872; 5,973,046; 5,976,443; 6,018,003;6,096,830; and PCT Patent Application Publication WO 99/48569.

Golf balls prepared in accordance with this invention comprise the hardionomer blend described herein replacing any traditional golf ballmaterial, or any golf ball cover, center, core, or intermediate layermaterial such as Surlyn® ionomer resin, balata rubber, thermoset orthermoplastic polyurethanes and the like.

A preferred embodiment of the thermoplastic composition of the inventionfor use in golf balls includes

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer;

(ii) from about 3 weight % to about 50 weight % of rosin, rosinderivative, or a combination of rosin and rosin derivative; andoptionally

(iii) from about 5 weight % to about 50 weight % of one or more organicacids or salts thereof; such that the combined weight % of component(ii) and component (iii) when present is from about 3 weight % to about60 weight % of the total composition; wherein the combined carboxylicacid functionalities in all ingredients in the blend are at leastpartially neutralized by one or more alkali metal, transition metal, oralkaline earth metal cations; provided that when component (ii) consistsof rosin ester, component (iii) must be present.

Of note is the composition comprising:

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer; and

(ii) from about 3 weight % to about 50 weight % of rosin; wherein thecombined carboxylic acid functionalities in all ingredients in the blendare at least partially neutralized by one or more alkali metal,transition metal, or alkaline earth metal cations.

As indicated, the golf balls of this invention can be produced byforming covers, mantles, or other intermediate layers comprising thehard ionomer blend around cores by molding processes. For example, incompression molding, the cover composition is formed via injection ate.g. about 380° F. to about 450° F. into smooth hemispherical shellswhich are positioned around the core in a dimpled golf ball mold andsubjected to compression molding at e.g. 200 to 450° F. for one to tenminutes, followed by cooling at 50 to 70° F. for one to ten minutes, tofuse the shells together to form a unitary ball. In one type ofinjection molding, the cover or mantle composition is injected directlyaround the core placed in the center of a golf ball mold for a period oftime at a mold temperature from about 50° F. to 150° F.

One-piece balls, cores and centers may be prepared by similar injectionmolding methods.

After molding, the golf balls produced may undergo various furtherprocessing steps such as buffing, painting and marking.

Said golf balls will have a traditional dimple pattern and may be coatedwith a polyurethane coating or be painted for appearance purposes, butsuch a coating and/or painting will not affect the performancecharacteristics of the ball. However, coating and/or painting may affectthe scuff resistance of the ball. In particular, such coating and/orpainting may improve scuff resistance over that of an unfinished ball.For the purposes of this invention, any coating and/or painting and/ormarking are not considered to be part of a golf ball cover.

One-piece Golf Ball

As used herein, the term “one-piece ball” refers to a golf ball moldedfrom a thermoplastic composition, i.e., not having elastomeric windings,cores or mantles and in which the whole ball is a homogeneous solidspheroid. As noted above, one-piece balls are manufactured by directinjection molding techniques or by compression molding techniques. Thehard ionomer blend described herein is used in such balls in combinationwith other materials typically used in these balls to prepare a golfball of this invention. Of note are one-piece golf balls in which acomposition of the invention forms the entirety of the ball.

As used herein, the term “multi-piece ball” refers to two-piece, 3-pieceand multilayer golf balls as described further below.

Two-piece Golf Ball

As used herein, the term “two-piece ball” refers to a golf ballcomprising a core and a cover. As noted above, two-piece balls may bemanufactured by first molding the core from a thermoset or thermoplasticcomposition, positioning these preformed cores in injection moldingcavities using retractable pins, then injection molding the covermaterial around the cores. Alternatively, covers can be produced bycompression molding cover material over the cores. The hard ionomerblend described herein can be used as the core, or preferably the coverof such golf balls to prepare a golf ball of this invention.

Three-piece Golf Ball

As used herein, the term “three-piece ball” refers to a golf ballcomprising a center, a traditional elastomeric winding wound around thecenter, and a cover. Three-piece golf balls may be manufactured bywell-known techniques as described in detail in, for example, U.S. Pat.No. 4,846,910. The hard ionomer blends described herein can be used asthe cover and/or the center of such golf balls to prepare a golf ball ofthis invention.

Multilaver Golf Ball

As used herein, the term “multilayer ball” refers to a golf ballcomprising a core, a cover, and one or more mantles or intermediatelayers between the core and the cover. As noted above, multilayer ballsmay be manufactured by first molding or making the core, typicallycompression or injection molding the mantle(s) over the core and thencompression or injection molding a cover over the mantle.

As indicated above, golf ball cores in multipiece balls may be solid orwound. Solid cores may be molded in one piece using compression orinjection molding techniques. A wound core is generally produced bywinding a very large elastic thread around a solid center or aliquid-filled balloon center. As indicated, additional mantle layers maybe applied over the core to produce a multilayer ball. For the purposesof this invention, the term solid core indicates a molded core withoutthe rubber band winding. Golf ball cores or centers typically comprisethermoset polyurethane or thermoplastic urethane resin.

The hard ionomer blends described herein can be used in the solid core,mantle, intermediate layers, or the cover of multipiece golf balls ofthis invention.

The specific combinations of resilience and compression used in thepractice of the subject invention will in large part be dependent uponthe type of golf ball desired (e.g., one-piece, two-piece, three-piece,or multilayer), and in the type of performance desired for the resultinggolf ball as detailed below. In addition, a golf ball typically mustmeet the maximum mass limit (not to exceed 45.93 grams) and minimum sizelimit (diameter not less than 1.680 inches or 42.67 mm) set by theUnited States Golfing Association (U.S.G.A.) or some other limit set bya golfer's governing authority. Preferably, the ball has a density ofabout 1.128 g/cm³.

In two-piece, three-piece or multilayer balls, sufficient filler may beadded to one or more components (i.e. core, mantle, intermediate layer,and/or covers) of the golf ball to adjust the mass of the golf ball to alevel meeting the limits set by the golfer's governing authority. Theabove described mass and size regulations are imposed on the golf balltaken as a whole. It follows that the density of a golf ball need not beconstant with respect to its radius. Accordingly, the densities ofvarious components of the ball comprising the thermoplastic compositionof the invention may be adjusted with filler(s) to varying values,including densities greater or less than 1.128 g/cm³, provided that thegolf ball as a whole does not exceed the maximum weight or fall belowthe minimum diameter requirements of the golfer's governing authority.Of note are one-piece balls wherein sufficient filler is added to thecomposition of this invention to adjust the density such that the massof a golf ball formed from the filled composition is adjusted to meetthe limits set by the golfer's governing authority. Preferably, enoughfiller is used so that the ball has a density of about 1.128 g/cm³.

Uses of the Hard Ionomer Composition in Other Applications

As indicated above, the thermoplastic compositions of the inventioncomprising an ionomer and a rosin, a rosin derivative, or both a rosinand a rosin derivative may be useful in a wide range of objects otherthan one-piece golf balls and covers, mantles, intermediate layers,cores, and centers of multipiece golf balls.

A preferred embodiment for use in objects other than golf ballscomprises

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer;

(ii) from about 3 weight % to about 50 weight % of rosin, rosinderivative, or a combination of rosin and rosin derivative; andoptionally

(iii) from about 5 weight % to about 50 weight % of one or more organicacids or salts thereof; such that the combined weight % of component(ii) and component (iii) when present is from about 3 weight % to about60 weight % of the total composition; wherein the combined carboxylicacid functionalities in all ingredients in the blend are at leastpartially neutralized by one or more alkali metal, transition metal, oralkaline earth metal cations.

Suitable and preferred optional components and concentration ranges areas described above in reference to the embodiments of the invention thatare useful in golf balls.

For example, the composition of the invention may be useful in othersporting equipment applications, particularly in golf shoe cleats,various components of golf clubs such as golf club face plates orinserts, molded golf club heads, club head coatings or casings, andfillers for inner cavity of a golf club head, and the like.

This composition may also be used in place of materials taught in theart for use in club faces, such as poly-imides reinforced with fillersor fibers, methyl (meth)acrylate copolymers, carbon-fiber reinforcedpolycarbonate, materials based on PMMA and crosslinkable monomers, andcross-linked synthetic rubber. This composition may also be substitutedfor the cured acrylic monomer, oligomer, polymer used to impregnate woodclub heads, for rubber-like elastic cores in club heads, and for moldedpolyurethane club heads. As such, golf club heads can be prepared havinga front striking face adapted to strike a ball and an insert mounted onthe striking face, said insert comprising a molded article comprisingthe composition above. In addition, golf club heads comprising a metalbody and an insert plate secured to the forward striking surface of themetal body and made of the composition above laminated with an outermetal layer formed with grooves. In addition, this invention alsoincludes a golf club having a shaft with a club head affixed to theshaft, wherein the club head is described above, having a componentcomprising the composition above.

The composition of the invention may also be useful for preparing moldedarticles that are footwear structural components, such as heel counters,toe puffs and soles as well as cleats for footwear. Footwear structuralcomponents such as heel counters, toe puffs, and soles provide shapesupport for footwear construction. The term “heel counter” as usedherein refers to a stiff, curved piece that provides shape and structureto the heel area of a shoe. The term “toe puff” (or “toe box”) as usedherein refers to a stiff, arched piece that provides shape and structureto the toe area of a shoe. The term “sole” as used herein refers to astiff, generally flat piece that provides shape and structure to thebottom of a shoe. These structural components are typically incorporatedinto the internal structure of the shoe and covered with additionalcomponents for wear and/or appearance.

See, for examples of materials and applications, particularly pertainingto golf equipment and shoes, U.S. Pat. Nos. 3,836,153; 4,326,716;4,504,520; 5,078,398; 6,146,571; EP 737,493B; FR 2523854A; GB 2132092B;JP 02124182A; JP 04144704A; JP 04002375A; JP 09225076A; JP 57203460A; JP59194802A; JP 62224382A; JP 3302407B; JP 92015702B; WO 2002004694; andWO 2002010470.

The composition of the invention may also be useful in non-sporting goodapplications such as caulking materials, sealants, modifiers for cementand asphalt, and coatings. In addition, the compositions of theinvention may also be useful in toys, decorative objects, and containersfor inert materials.

Of particular note are the following embodiments of the invention:

-   1. A thermoplastic composition comprising:

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer;

(ii) from about 3 weight % to about 50 weight % of rosin; or from about3 weight % to about 50 weight % of rosin ester; and optionally

(iii) from about 5 weight % to about 50 weight % of one or more organicacids or salts thereof; such that the combined weight % of component(ii) and component (iii) when present is from about 3 weight % to about60 weight % of the total composition; wherein the combined carboxylicacid functionalities in all ingredients in the blend are at leastpartially neutralized by one or more alkali metal, transition metal, oralkaline earth metal cations; provided that when component (ii) consistsof rosin ester, component (iii) must be present.

2. Composition 1 comprising

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer; and

(ii) from about 3 weight % to about 50 weight % of rosin; wherein thecombined carboxylic acid functionalities in all ingredients in the blendare at least partially neutralized by one or more alkali metal,transition metal, or alkaline earth metal cations.

3. Composition 1 or 2 further comprising at least one additionalcomponent selected from non-ionomeric thermoplastic polymers.

4. Composition 3 wherein said at least one non-ionomeric thermoplasticpolymer is selected from the group consisting of polyurethanes;polyureas; polyamides; polyesters; polystyrenes; acrylic polymers;polycarbonates; copoly-ether-esters; copoly-ether-amides;copoly-ether-urethanes; copoly-ether-ureas; polyolefins; elastomericpolyolefins; ethylene-propylene-diene monomer polymer;metallocene-catalyzed polyethylenes and polypropylenes; ethylenecopolymers with polar comonomers such as vinyl acetate, alkyl(meth)acrylates, carbon monoxide, and epoxy-containing comonomers;maleic anhydride modified polymers; and thermoplastic elastomers basedon styrene-butadiene block copolymers and derivatives.

5. Compositions 1 through 4 exhibiting Shore D hardness greater than orequal to about 60.

6. Composition 5 exhibiting Shore D hardness greater than or equal to65.

7. Composition 6 exhibiting Shore D hardness greater than or equal to70.

8. Compositions 1 through 4 exhibiting flex modulus greater than orequal to 60 kpsi.

9. Composition 8 exhibiting flex modulus greater than or equal to 65kpsi.

10. Composition 9 exhibiting flex modulus greater than or equal to 70kpsi.

11. Composition 10 exhibiting flex modulus greater than or equal to 75kpsi.

12. Composition 11 exhibiting flex modulus greater than or equal to 80kpsi.

13. Composition 12 exhibiting flex modulus greater than or equal to 90kpsi.

14. Composition 13 exhibiting flex modulus greater than or equal to 100kpsi.

15. A one-piece golf ball comprising one or more of compositions 1through 14.

16. Golf ball 15 wherein sufficient filler is added to the compositionused to prepare the golf ball to adjust the mass of the golf ball to alevel meeting the limits set by the golfer's governing authority.

17. A one-piece golf ball consisting essentially of one or more ofcompositions 1 through 14.

18. A multi-piece golf ball wherein any of the following components thatform the golf ball selected from the group consisting of the cover, themantle, any intermediate layer, the core and the center comprises one ormore of thermoplastic compositions 1 through 14.

19. Golf ball 18, wherein at least one of said components that form thegolf ball comprises one or more of compositions 1 through 14 and atleast one other component comprises a non-ionomeric thermoplasticpolymer.

20. Golf ball 18 having a cover comprising one or more of compositions 1through 14.

21. Golf ball 19 having a core of a thermoplastic or thermosetcomposition, a mantle or intermediate layer comprising one or moreofthermoplastic compositions 1 through 14, and a relatively softercover.

22. Golf ball 21 wherein the cover comprises a thermoset polyurethane orthermoplastic urethane resin.

23. A multi-piece golf ball wherein any of the following components thatform the golf ball selected from the group consisting of the cover, themantle, any intermediate layer, the core and the center consistsessentially of at least one of thermoplastic compositions 1 through 14.

24. Golf balls 18 through 23 wherein sufficient filler is added to oneor more components of the golf ball to adjust the mass of the golf ballto a level meeting the limits set by the golfer's governing authority.

25. A molded article selected from the group consisting of sports shoecleats, golf club face plates or inserts, molded golf club heads, clubhead coatings or casings, fillers for the inner cavity of a golf clubhead, and footwear structural components comprising a thermoplasticcomposition comprising:

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer;

(ii) from about 3 weight % to about 50 weight % of rosin, rosin ester,or both rosin and rosin ester; and optionally

(iii) from about 5 weight % to about 50 weight % of one or more organicacids or salts thereof; such that the combined weight % of component(ii) and component (iii) when present is from about 3 weight % to about60 weight % of the total composition; wherein the combined carboxylicacid functionalities in all ingredients in the blend are at leastpartially neutralized by one or more alkali metal, transition metal, oralkaline earth metal cations; and optionally further comprising at leastone non-ionomeric thermoplastic resin.

26. The molded article 25 that is a footwear structural componentselected from the group consisting of heel counters, toe puffs, andsoles.

27. A caulking material, sealant, modifier for cement and asphalt, orcoating comprising a thermoplastic composition comprising:

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer;

(ii) from about 3 weight % to about 50 weight % of rosin, rosin ester,or both rosin and rosin ester; and, optionally,

(iii) from about 5 weight % to about 50 weight % of one or more organicacids or salts thereof; such that the combined weight % of component(ii) and component (iii) when present is from about 3 weight % to about60 weight % of the total composition; wherein the combined carboxylicacid functionalities in all ingredients in the blend are at leastpartially neutralized by one or more alkali metal, transition metal, oralkaline earth metal cations; and optionally further comprising at leastone non-ionomeric thermoplastic resin.

28. A golf club having a shaft with a club head affixed to the shaft,the club head having a front striking face adapted to strike a ball andan insert mounted on the striking face, said insert comprising moldedarticle 25.

29. A golf club head comprising a metal body and an insert plate securedto the forward striking surface of the metal body and made of acomposition comprising:

(i) at least one E/X/Y copolymer where E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate whereinthe alkyl groups have from one to eight carbon atoms, wherein X is fromabout 2 to about 30 weight % of the E/X/Y copolymer and Y is from 0 toabout 40 weight % of the E/X/Y copolymer;

(ii) from about 3 weight % to about 50 weight % of rosin, rosin ester,or both rosin and rosin ester; and, optionally,

(iii) from about 5 weight % to about 50 weight % of one or more organicacids or salts thereof; such that the combined weight % of component(ii) and component (iii) when present is from about 3 weight % to about60 weight % of the total composition; wherein the combined carboxylicacid functionalities in all ingredients in the blend are at leastpartially neutralized by one or more alkali metal, transition metal, oralkaline earth metal cations; and optionally further comprising at leastone non-ionomeric thermoplastic resin; said composition laminated withan outer metal layer formed with grooves.

31. A method of increasing the hardness and/or stiffness of an ionomerby blending the ionomer with a rosin, a rosin ester, or both a rosin anda rosin ester.

32. A method of increasing the coefficient of resilience of a golf ballby providing an ionomer, blending the ionomer with a rosin, a rosinester, or both a rosin and a rosin ester to form an ionomer blend, andforming the ionomer blend into a core, a center, a mantle, a layer, acover, or the entirety of the golf ball.

33. A method of increasing the hardness and/or stiffness of a golf ballby providing an ionomer, blending the ionomer with a rosin, a rosinester, or both a rosin and a rosin ester to form an ionomer blend, andforming the ionomer blend into a core, a center, a mantle, a layer, acover, or the entirety of the golf ball.

Without further elaboration, it is believed that one skilled in the artusing the preceding description can utilize the present invention to itsfullest extent. The following examples are provided to describe theinvention in further detail. These examples, which set forth a preferredmode presently contemplated for carrying out the invention, are intendedto illustrate and not to limit the invention.

EXAMPLES

Analytical Protocols

Melt Index (MI) was measured in accord with ASTM D-1238, condition E, at190° C., using a 2160-gram weight, with values of MI reported ingrams/10 minutes.

Shore D hardness was determined in accord with ASTM D-2240. Shore Dhardness was also measured on the neat resin spheres as reported.

Coefficient of Restitution (COR) is a measurement of the elasticproperties of a sphere and is an indicator of the resilience of itscomposition, that is, its ability to rebound after impact. The COR ismeasured by firing a sphere, having a size approximately 1.51 inches indiameter, from an air cannon at a fixed velocity determined by the airpressure within the barrel of the cannon. The sphere can be aninjection-molded neat sphere of the test resin, or it can be amulti-piece ball. The sphere strikes a steel plate positioned three feetaway from the point where initial velocity is determined, and reboundsthrough a speed-monitoring device located at the same point as theinitial velocity measurement. The return velocity divided by the initialvelocity is the COR. The initial velocity generally employed is 125feet/second (COR-125).

Atti Compression (Atti Comp.), also known as PGA Compression, is definedas the resistance to deformation of a golf ball, measured using an AttiCompression Gauge. The Atti Compression Gauge is designed to measure theresistance to deformation or resistance to compression of golf ballsthat are 1.680 inches in diameter. In these examples, smaller spheresapproximately 1.51 inches in diameter were used. Spacers or shims weretherefore used to compensate for this difference in diameter. After thesphere diameters were measured, one or more shims of differentthicknesses were selected to correct the sphere diameter plus total shimthickness to within 0.0025 inches of 1.680 inches.

After the PGA compression of the sphere and shim(s) was measured, theresulting value was mathematically corrected, using standard methods, tocompensate for the deviation of the diameter of the sphere from theideal of 1.680 inches. Specifically, if the sphere diameter plus shimthickness was less than 1.680 inches, one compression unit was added forevery 0.001 inch less than 1.680 inches. If the sphere diameter plusshim thickness was greater than 1.680 inches, one compression unit wassubtracted for every 0.001 inch greater than 1.680 inches.

Impact durability was determined by firing two-piece golf balls havingthe hard ionomer composition of the invention as the cover over acommercial thermoset polybutadiene core at a steel plate at 175 feet persecond repeatedly until the golf ball cracks upon impact with the steelplate. The durability, or number of hits against the steel plate, asreported herein, is the average durability measured for three golfballs.

Materials used

Non-neutralized ethylene/(meth)acrylic acid copolymers are commerciallyavailable from DuPont under the trade name Nucrel®. Ionomer base resinsare commercially available from DuPont under the trade name Surlyn®. Theionomers used in the Examples are derived from ethylene/(meth)acrylicacid copolymers with either 15 weight % or 19 weight % methacrylic acidthat have melt indices (MI) of about 60. The ethylene/(meth)acrylic acidcopolymers are neutralized under standard conditions to provide theionomer resins. Ionomer resins used in these Examples include thefollowing:

Table of Ionomer Resins A: E/15% MAA, 47% neut. w. Li, B: E/15% MAA, 52%neut. w. Li,   with MI of 2.6.   with MI of 1.8 C: E/15% MAA, 59% neut.w. Na, D: E/19% MAA, 37% neut. w. Na,   with MI of 0.93   with MI of 2.6E: E/19% MAA, 36% neut. w. Zn, F: E/19% MAA, 40% neut. w. Mg,   with MIof 1.3   with MI of 1.1 G: E/19% MAA, 45% neut. w. Li,   with MI of 1.1Notes for Table of Ionomer Resins: E represents ethylene, MAA representsmethacrylic acid, and the percentages of MAA represent the weight % ofMAA present in the copolymer. The neutralization level is given as thepercentage of the available carboxylic acid moieties neutralized, andthe atomic symbol of the neutralizing cation is listed.

Rosin salt is commercially available from Resinall Corporation ofStamford, Conn. (Resinall) under the tradename Resinall™. Grades usedinclude the following:

Rosin H: Resinall ™ 153 (9% ZnO I: Resinall ™ 154 (6%   modified rosinresinate)   ZnO modified rosin   resinate)

Compositions according to the invention were prepared by melt blendingthe ionomer resins and the rosin salt modifier employing a Werner &Pfleiderer twin-screw extruder. After blending, the compositions wereextruded into the appropriate shapes for mechanical property testing.

Comparative Examples are the ionomers or ionomer blends without therosin modifier, prepared and extruded in similar fashion. They arenumbered to correspond to the Examples of the compositions of theinvention (e.g. Examples 1 and 4 use the same ionomer base resin asComparative Example C1/4; however, Examples 1 and 4 also contain therosin indicated). In Tables 1 and 2, the term “- -” indicates that acomponent is not present in the composition.

In the compositions set forth below as Examples and ComparativeExamples, the percentage given for each component refers to a weightpercent based on the total weight of the thermoplastic blend, unlessotherwise indicated in specific instances.

EXAMPLES 1-13 AND COMPARATIVE EXAMPLES

Thermoplastic compositions of the invention prepared as Examples 1through 13 are reported in Table 1. The compositions were injectionmolded into flex bars for mechanical property tests. After two weeks ofannealing at ambient temperature (approximately 23° C.), the Shore Dhardness was measured and is reported in Table 1. The compositions werealso injection molded and, as resin spheres, tested for golf ballproperties after more than two weeks of aging at ambient temperature.The Atti compression and the coefficients of restitution of the neatspheres are also reported in Table 1.

TABLE 1 Exam- Neat Resin Sphere Property ple Ionomer Ionomer Rosin AttiComp. COR-125 Shore D  1  80% A — 20% H 162 0.717 66  2  80% B — 20% H160 0.715 66  3  80% C — 20% H 157 0.691 65  4  80% A — 20% I 157 0.71365  5  80% B — 20% I 158 0.712 66  6  80% C — 20% I 158 0.699 65  7  40%A 40% C 20% H 158 0.714 67  8  40% B 40% C 20% H 160 0.714 67  9  40% D40% E 20% H 167 0.74  70.4 10  40% D 40% F 20% H 167 0.747 71.2 11  40%D 40% G 20% H 165 0.749 70.8 12  40% E 40% G 20% H 169 0.74  70.7 13 40% F 40% G 20% H 169 0.735 70 C1/4 100% A — — 153 0.738 63 C3/6 100% C— — 150 0.732 62 C7   50% A 50% C — 154 0.741 63 C9   50% D 50% E — 1600.746 63.2 C10  50% D 50% F — 159 0.767 65.7 C11  50% D 50% G — 1610.768 65.8 C12  50% E 50% G — 156 0.754 63.7 C13  50% F 50% G — 1600.764 66.1 14  40% A 40% C 20% I 157 0.713 64 15  40% B 40% C 20% I 1590.715 65

The data presented in Table 1 show that the rosin-modified ionomers ofthis invention exhibit increased Shore D hardness and Atti compressioncompared to the non-modified ionomers (see, for example, the comparisonbetween Examples 1 and 4 versus Comparative Example C1/4). Also,rosin-modified ionomers with lower acid comonomer content can behardened to Shore D values comparable to or exceeding those exhibited bynon-modified ionomers with higher acid comonomer content (see, forexample, the comparison between Examples 1 and 4 versus ComparativeExample C9).

EXAMPLES 21-28, 31-36 AND COMPARATIVE EXAMPLES

Thermoplastic compositions of this invention designated as Examples 21through 28 and 31 through 36 are reported in Table 2. These compositionswere injection molded into flex bars for mechanical property tests.After two weeks of annealing at ambient temperature (approximately 23°C.), the Shore D hardness and the flex moduli were measured. Inaddition, the compositions were injection molded into neat resin spheresand tested for golf ball properties after more than two weeks of agingat ambient temperature. The Atti compressions, Shore D hardness, and thecoefficients of restitution of the neat spheres are also reported inTable 2.

TABLE 2 Material Property Neat Resin Sphere Property Flex Shore Shore DMod. Atti COR- D Ex. Ionomer Ionomer Rosin Hardness (kpsi) Comp. 125hardness 21 47.5% B 47.5% C  5% H 61 63.7 154 0.728 66 22   45% B   45%C 10% H 62 66.3 157 0.721 67 23   40% B   40% C 20% H 65 77.8 159 0.70268 24   35% B   35% C 30% H 66 85.4 162 0.684 70 25 47.5% D 47.5% F  5%H 67 81.9 159 0.751 67 26   45% D   45% F 10% H 66 81.6 163 0.741 69 27  40% D   40% F 20% H 68 97.2 161 0.727 71 28   35% D   35% F 30% H 6699.9 166 0.712 72 C21-24   50% B   50% C — 63 59.5 150 0.736 64 C25-28  50% D   50% F — 66 79.5 160 0.756 67 31   80% A — 20% H 69.5 91.7 1600.709 69 32   75% A — 25% H 71.8 96 162 0.700 69 33   40% D   40% F 20%H 71.3 109.7 164 0.729 71 34 37.5% D 37.5% F 25% H 73 117.6 165 0.724 7135   40% D   40% G 20% H 70.8 111.2 164 0.739 71 36   40% D   40% G 25%H 74 116.9 167 0.731 72 C33/34   50% D   50% F — NA NA 160 0.756 67

The data presented in Table 2 show that the rosin-modified ionomers ofthis invention exhibit either increased Shore D hardness and/or flexmodulus compared to the non-modified ionomer (see, for example, thecomparison between Examples 21 and 24 versus Comparative ExampleC21-24). Examples of rosin-modified ionomers with lower acid comonomercontent can be hardened to Shore D values comparable to or exceedingthose exhibited by non-modified ionomers with higher acid comonomercontent (see, for example, the comparison between Example 24 versusComparative Example C25-28).

The data in Table 2 also indicate that the hard ionomer blends of thisinvention exhibit flex moduli ranging from about 60 to about 120.

Moreover, certain hard ionomer blends of the invention exhibit meltindices ranging from about 1 to about 3, as shown in Table 3, indicatingthat the invention provides the potential to select more favorableprocessing conditions for relatively harder or stiffer materials.

TABLE 3 Example Ionomer Ionomer Rosin M. I. 31 80% A — 20% H 2.3 32 75%A — 25% H 2.2 33 40% D 40% F 20% H 1.3 34 37.5% D   37.5% F   25% H 1.335 40% D 40% G 20% H 1.1 36 40% D 40% G 25% H 1.1

EXAMPLES 37 to 42 AND COMPARATIVE EXAMPLES

Examples 37 to 42 and Comparative Examples C39 and C43 were prepared byinjection molding the compositions of Examples 31 to 36, C33/34, andC21-24, respectively (as indicated in Table 4) over identicalconventional thermoset polybutadiene cores to prepare two-piece balls.

TABLE 4 Cover Composition Atti COR- Shore D Impact Example (From Table2) Comp. 125 hardness Durability 37 31  92 0.781 68 6.4 38 32  98 0.78469 10.6 39 33 105 0.800 70 13.4 40 34 103 0.790 70 12.4 C39 C33/34 1020.791 67 36 41 35 103 0.793 71 10.2 42 36 107 0.793 71 10.0 C43 C21-24 94 0.779 65 26.2

These results demonstrate that a two-piece ball (e.g., Example 39)covered with a stiffer composition of this invention (e.g., Example 33)exhibits a higher COR than that exhibited by a 2-piece ball (ComparativeExample C39) consisting of an identical thermoset core covered with amore resilient composition (e.g., Comparative Example C33). Thus,although Example 33 has a lower COR than Comparative Example C33 (whentested as a neat resin sphere as reported in Table 2), when used as acover over a thermoset core in a 2-piece ball, it provides enhancedresilience.

EXAMPLES 43-48

Hard ionomer compositions of this invention prepared as Examples 43through 48 are reported in Table 5. The compositions were injectionmolded into flex bars for mechanical property tests. After two weeks ofannealing at ambient temperature (approximately 23° C.), the Shore Dhardness and the flex moduli were measured as described below and arereported in Table 5.

TABLE 5 Ex- Flex am- Hardness, modulus, ple Ionomer Ionomer Rosin M.I.Shore D kpsi 43 37.5% D 37.5% F 25% P 13.9 73 81 44 37.5% D 37.5% F 25%R 12.6 74 117  45 37.5% D 37.5% F 25% S 9.5 68 81 46 37.5% D 37.5% F 25%V 7.5 75 135  47 37.5% D 37.5% F 25% VN 0.6 74 93 48 37.5% D 37.5% F 25%J 1.6 74 76 Key to rosins in Table 5: P: Poly-Pale ™, a partiallydimerized rosin available from Eastman R: Dymerex ™, a dimerized rosinavailable from Eastman S: Staybelite ™ A, a partially hydrogenated rosinavailable from Eastman V: Vinsol ™, a dark rosin available from EastmanVN: Vinsol ™ NVX, a sodium salt of Vinsol ™, available from Eastman J:Resinal ™ 130, available from Resinall

The data in Table 5 demonstrate that rosin type has a highly significanteffect on the physical properties of the rosin-ionomer blends. Forexample, the melt indices of otherwise identical blends that differedonly in the choice of rosin ranged over more than an order of magnitude.Similarly, the greatest variation between flex moduli in this series isapproximately a factor of two.

It is also apparent from the results in that the properties of thethermoplastic composition of the invention may be tailoredsystematically through resin choice. The ratio of flex modulus tohardness, for example, varies by a factor of two depending on rosinchoice alone.

EXAMPLES 49-50

Hard ionomer compositions of this invention prepared as Examples 49 and50 are reported in Table 6. The compositions were injection molded intoflex bars for mechanical property tests. After two weeks of annealing atambient temperature (approximately 23° C.), the Shore D hardness and theflex moduli were measured and are reported in Table 7.

TABLE 6 Organic acid Example Ionomer salt Mg(OH)2 Rosin MI 49 48% F31.04% 0.96% 20% H 0.42 Ca stearate Mg(OH)2 50 42% F 27.16% 0.84% 30% H0.47 Ca stearate Mg(OH)2

TABLE 7 Plaque Hardness Flex modulus, Example Shore D kpsi 49 65 42 5066 40

The data in Table 7 demonstrate that the addition of organic acid saltsto the thermoplastic blends of the invention results in a numericallowering of all measured physical properties when compared to similarexamples that do not include organic acid salts, e.g., Example 10 andComparative Example C25-28.

Having thus described and exemplified the invention with a certaindegree of particularity, it should be appreciated that the followingclaims are not to be so limited but are to be afforded a scopecommensurate with the elements of the following claims and theequivalents thereof.

1. A golf club having a shaft with a club head affixed to the shaft, theclub head having a metal body, a front striking face adapted to strike aball and an insert plate mounted on the striking face, said insertcomprising a molded article, said molded article comprising athermoplastic composition comprising: (i) at least one E/X/Y copolymerwherein E represents copolymerized residues of ethylene, X representscopolymerized residues of a C₃ to C₈ α, β-ethylenically unsaturatedcarboxylic acid, and Y represents copolymerized residues of a softeningcomonomer selected from alkyl acrylate and alkyl methacrylate, whereinthe alkyl groups have from one to eight carbon atoms, wherein the amountof X is from about 2 to about 30 weight % of the E/X/Y copolymer,wherein the amount of Y is from 0 to about 40 weight % of the E/X/Ycopolymer, and wherein the carboxylic acid functionalities are at leastpartially neutralized by one or more alkali metal, transition metal, oralkaline earth metal cations; and (ii) at least one rosin, at least onerosin derivative, or both a rosin and a rosin derivative.
 2. The golfclub head of claim 1, wherein said molded article is laminated with anouter metal layer, said outer metal layer comprising grooves.
 3. Thegolf club of claim 1, wherein the composition further comprises at leastone non-ionomeric thermoplastic polymer.
 4. The golf club of claim 3,wherein said at least one non-ionomeric thermoplastic polymer isselected from the group consisting of polyurethanes; polyureas;polyamides; polyesters; polystyrenes; acrylic polymers; polycarbonates;copoly-ether-esters; copoly-ether-amides; copoly-ether-urethanes;copoly-ether-ureas; polyolefins; elastomeric polyolefins;ethylene-propylene-diene monomer polymer; metallocene-catalyzedpolyethylenes and polypropylenes; ethylene copolymers with polarcomonomers; maleic anhydride modified polymers; and thermoplasticelastomers based on styrene-butadiene block copolymers and derivatives.5. The golf club of claim 1 wherein the at least one rosin, the at leastone rosin derivative, or both the rosin and the rosin derivative arepresent in an amount of from about 3 weight percent to about 50 weightpercent.
 6. The golf club of claim 1, further comprising one or moreorganic acids, one or more salts of organic acids, or both an organicacid and a salt of an organic acid, provided that said one or moreorganic acids and one or more salts of organic acids do not compriserosin acids or salts of rosin acids.
 7. The golf club of claim 6,wherein the combination of rosin, rosin derivative, organic acids andsalts of organic acids is present in an amount of 3 weight percent toabout 60 weight percent.
 8. The golf club of claim 6, wherein theorganic acid or organic acid salt is aliphatic and mono-functional; andwherein the organic acid or organic acid salt is saturated, unsaturated,or multi-unsaturated.
 9. The golf club of claim 6, wherein the organicacid or organic acid salt has from 6 to 36 carbon atoms.
 10. The golfclub of claim 6, wherein the organic acid or organic acid salt is linearand saturated.
 11. The golf club of claim 6, wherein the organic acid ororganic acid salt is selected from the group consisting of caproic acid,caprylic acid, capric acid, lauric acid, stearic acid, behenic acid,palmitic acid, myristic acid and the salts thereof.
 12. The golf club ofclaim 6, wherein the organic acid or organic acid salt is selected fromthe group consisting of stearic, behenic, palmitic and myristic acidsand the salts thereof.
 13. The golf club of claim 1, wherein thethermoplastic composition has a Shore D hardness greater than or equalto about
 60. 14. The golf club of claim 1, wherein the thermoplasticcomposition has a Shore D hardness greater than or equal to about 70.15. The golf club of claim 1, wherein the thermoplastic composition hasa flex modulus greater than or equal to 65 kpsi.
 16. The golf club ofclaim 1, wherein the thermoplastic composition has a flex modulusgreater than or equal to 100 kpsi.
 17. The golf club of claim 1 whereinthe at least one rosin derivative comprises at least one rosin salt. 18.The golf club of claim 1 wherein the thermoplastic composition furthercomprises one or more additives selected from the group consisting offillers, whitening agents, pigments, optical brighteners, surfactants,processing aids, fibers, and stabilizers.